Lubricant compositions containing rust inhibitors



United States Patent 3,434,972 LUBRICANT COMPOSITIONS CONTAINING RUSTINHIBITORS Warren Lowe, El Cerrito, Calif., assignor to Chevron ResearchCompany, San Francisco, Calif., a corporation of Delaware No Drawing.Filed Nov. 30, 1966, Ser. No. 597,876 Int. Cl. C10m N32 US. Cl. 25251.55 Claims ABSTRACT OF THE DISCLOSURE Lubricant composition havingimproved rust inhibiting properties containing an alkenyl succinimidedetergent additive and as a rust inhibiting additive a diurethane of apentaerythritol monocarboxylate.

This invention relates to lubricant compositions inhibited from rusting.More particularly, it relates to lubricants containing ashlessnitrogen-containing detergents which have a propensity to promoterusting and as an inhibitor for the rusting, a diurethane formed from apentaerythritol monocarboxylate.

Within recent years, it has become common practice to impart improvedproperties to lubricants by the addition of certain additives. Ofparticular importance in the operation of internal combustion engines isthe use of certain compounds which function to present the accumulationof deposits such as varnish-like coating on pistons, cylinder walls andother operating parts of engines. These Compounds which act to disperseaccumulated solids in the oil are known as dispersant or detergent-typeadditives.

Among the more successful detergent additives which have been introducedare the oil-soluble, high molecular weight basic nitrogen-containingcompounds. Included among these materials are alkenyl succinimides andhydrocarbyl polyamines. These materials possess superior detergentcharacteristics and are employed in a variety of lubricant compositions.One of the primary reasons for employing these types of materials istheir so-called ashless quality. That is, when they enter the combustionchamber of the engine and along with the fuel are combusted, they do notleave metallic ion-containing deposits which contribute to engine wearand loss of efiiciency. However, concomitant with their increaseddetergency and lack of metal-containing deposits, these materials have atendency to promote oxidation of iron and steel surfaces. Thus, alubricant containing one of these types of detergents will often fail toinhibit and often promote rusting of engine surfaces, particularl whenthe engine is at rest. It is thus desirable to incorporate in thelubricants materials which will inhibit rusting.

It has now been found that ashless lubricant compositions possessingexcellent detergency characteristics and nonrusting characteristics canbe formulated from a major portion of an oil of lubricating viscosityand minor portions of free amino group containing detergents, such asalkenyl succinimides of polyalkylene polyamines andhydrocarbyl-substituted polyalkylene polyamines, and as a rustinhibitor, a diurethane of the formula:

3,434,972 Patented Mar. 25, 1969 in which X and Y represent hydrogen ora carboxy acyl group of from about 10 to 24 carbon atoms, Ar representsan arylene group of from 6 to 15 carbon atoms, and one X and one Y arecarboxy acyl.

The rust inhibitors of this invention can be most conveniently describedas diurethanes or arylene diisocyanates and pentaerythritolmonocarboxylate. The acyl radicals are derived from alkyl or alkenylcarboxylic acids or anhydrides of 10 to 24 carbon atoms. Thus, examplesof suitable acids are decanoic, undecanoic, tridecanoic acids, etc. Alsoincluded among the suitable acids are the fatty acids or naturallyoccurring straight-chain, saturated and unsaturated aliphatic acids suchas palmitic acid, stearic acid, oleic acid, linoleic acid, linolenicacid, etc.

Ar is derived from an arylene diisocyanate. Examples of suitablediisocyanates include the various benzene diisocyanates, tolylenediisocyanates, xylylene diisocyanates, biphenylene diisocyanate, cumenediisocyanate, diphenylmethane diisocyanate, etc.

The diurethane additive of this invention is most conveniently preparedby simply heating together two mols of the pentaerythritolmonocarboxylate and one mol of the arylene diisocyanate at temperaturesin the range of from 40 to about 125 C.

The following example illustrates the Preparation of the diurethaneadditive.

EXAMPLE 800 gms. (2 mols) of pentaerythritol monooleate was charged to a3-necked flask equipped with a thermometer, water condenser, heatingmantle and stirrer. The material was heated with stirring to about 50 C.and a total of 184 grams (1 mol) of tolylene diisocyanate was addedslowly. The temperature of the reaction mixture was raised and heated ata temperature of from about to C. for a period of eight hours. Thereaction mixture was allowed to cool, yielding a rather viscousmaterial.

In order to demonstrate the rust-inhibiting characteristics of the lubecompositions of this invention, the compositions were subjected to theCLR Rusting Test. This test, employing the single cylinder CooperativeLubrication Research Engine, involved operating the engine under thefollowing conditions:

Engine speed r.p.m 1800 Fuel rate lbs./hr 4.4 Air to fuel ratio a- 14/1Jacket water temperature, out F Oil temperature F Intake air moisturegrams H O/lb. of air 80 Intake air temperature F The test was conductedaccording to the following procedure: Two rusting test strips wereplaced in the crankcase, and the crankcase was filled with the subjecttest oil. The engine was operated for 15 hours under the above-describedconditions. The engine was then stopped and the parts removed andinspected for rusting. The parts were then given a CRC Rust Rating on ascale of zero to 10, with zero being completely rust-covered and 10being clean. An average rating was determined for the following parts:valve lifter body, plunger, and ball check; push rods, oil pressurerelief ball, and crankcase test strips. When the average rating 'wasabove eight, the engine was reassembled and run under the standardoperating condition for the additional five hours. The engine was thendisassembled and the parts again rated. This procedure was repeateduntil the average rusting rating dropped below eight.

Rusting tests were performed using as a lubricant base a solvent-refinedparaflinic neutral oil of SAE 20 grade containing 2.0% by weight of apolybutenyl succinimide detergent additive. The detergent was preparedby heating one mol of polybutenyl succinic anhydride having about 65carbon atoms in the alkenyl chain with 0.9 mol of tetraethylenepcntamine. In addition, the oil contained 10 mm./kg. of a zincditisobutyl-mixed primary hexyl) dithiophosphate and 2 mrn./l g. of zincdi(polypropylphenyl)dithiophosphate. Comparative tests were made usingthe reference oil containing the diurethane and samples of the referenceoil containing tetrapropenyl succinic acid, and highly successfulcommercial rust inhibitor. The testing sequence was performed by runningthe engine with the reference oil and the succinic acid inhibitor,determining the rust rating, cleaning the engine parts and running thetest with the reference oil plus various amounts of the diurethaneinhibitor. Data from these tests is given in the following table:

TABLE.(.LR ENGINE RUST TEST As can be seen from these data, the subjectdiurethane inhibitor compares very favorably with the substitutedsuccinic acid as a rust inhibitor, giving a 27 hour test at 2%concentration.

The diurethane inhibitor of this invention is employed in amountssufficient to inhibit oxidation of ferrous surfaces, generally of fromabout 0.5 to 5% by weight of the lubricant composition. Amounts of fromabout 1 to 4% are preferred.

The detergents employed in the compositions of this invention are therecently developed nitrogen-containing nonmetallic acid detergents.Examples of these detergents are those derived from alkenyl succinicanhydrides having 30, preferably 50 or more, carbon atoms in the alkenyl group and amine compounds such as tetraethylene pentamine,N-aminoethyl piperazine, dimethyl aminopropylene, etc. The detergentadditive is generally obtained by adding one mol of an alkenyl succinicanhydride with at least 0.5 mol of an amine.

The substituted succinic anhydrides contemplated as reactants in theprocess can be readily obtained by heating maleic anhydride with a highmolecular weight olefin or with a chlorinated high molecular weightolefin at a temperature of from about 150 to 200 C. Typical highmolecular weight olefins which may be so employed are polyethylene,polypropylene, polyisobutylene, etc. Polyisohutylene is preferred.

Examples of suitable polyalkylene polyamine reactants are ethylenediamine, diethylene triamine, tetraethylene pentamine, and the like.Tetraethylene pentamine is the preferred polyamine reactant.

A preferred embodiment of the detergent additive is the product obtainedby heating one mol of a polyisobutenyl succinic anhydride having about65 carbon atoms in the olefin chain with 0.9 mol of tetraethylenepentamine.

The detergent additive is employed in the lubricant composition in anamount sufiicient to impart detergency. Generally, amounts of from 0.1to 10% by Weight are preferred.

Any of the well-known types of lubricating oils can be used as the baseoil for the compositions of this invention. These oils are corrosive tometal surfaces under normal operating conditions. Examples of such baseoils are naphthenic base, paraflin base, and mixed base mineral oils;synthetic oils, e.g., alkylene polymers, such as polymers of propylene,butylene, etc. and mixtures thereof; alkylene oxide type polymers;clicarboxylic acid esters; phosphorus esters; silicone esters, such assilicates and polysiloxanes; and alkyl aromatic hydrocarbons.

The additives of this invention are effective in lubricant compositionscontaining additional conventional additives, such as oxygen inhibitors,supplementary detergents, sludge inhibitors, pour depressants, VIimprovers, antifoarning agents, rust inhibitors, oiliness agents, wearinhibitors, dyes, etc.

While the character of this invention has been described in detail, thishas been done by way of illustration only and without limitation of theinvention. It will be apparent to those skilled in the art that numerousmodifications and variations of the illustrative examples can be made inthe practice of the invention Within the scope of the appended claims.

I claim:

1. A lubricant composition comprising a major portion of an oil oflubricating viscosity, a minor portion sufiicient to impart detergencyof an alltenyl succinimide detergent and a minor portion sufiicient toinhibit rusting of ferrous surfaces at diurethane of the formula:

in which X and Y are hydrogen or a carboxy acyl group of 10 to 24 carbonatoms, Ar is an arylene group of 6 to 15 carbon atoms and only one X andone Y are carboxy acyl.

2. The composition of claim 1 in which the carboxy acyl groups areoleyl.

.3. The composition of claim 2 in which Ar is tolylene.

4. The composition of claim 1 in which the detergent additive is apolybutenyl succinimide prepared from a polybutenyl succinic anhydridehaving about 65 carbon atoms in the alkenyl chain and tetraethylenepentamine.

5. The composition of claim 4 wherein the polybutenyl succinimide ispresent in the amount of from 0.1 to 10% by weight and the diurethanefrom about 0.5 to 5% by weight.

References Cited UNITED STATES PATENTS 2,987,515 6/1961 Stromberg et al.3,096,285 7/1963 Huttenlocher et al. 3,172,892 3/1965 Le Suer et al.3,189,629 6/1965 Huttenlocher et al. 3,361,673 1/1968 Stuart et a1.

PATRICK l. GARVIN, Primary Examiner.

U.S. Cl. X.R. 252392

